if the plasma is all surrounded by a magnetic field, then how does the heat get transmitted outside the field?how does the heatexchanger work and the moderator?
The plasma chamber of the tokamak is surrounded by a blanket of lithium (the moderator). It is this lithium blanket that absorbs the high energy fast neutrons that are the product of the fusion reaction, and gets heated up as a result. (The walls of the plasma chamber allow the neutrons to pass through readily.) The lithium in turn is surrounded by water (the coolant) which gets circulated to a heat exchanger to provide steam, and then ultimately pumped back to cool the lithium again. All in all, a round-about process that just may work some day (at least another 30 years before they get all the tough technical issues worked out).
